The VIIA Britanica, a railway carrying unaccompanied trailers from Spain through France to Britain, decided to stop its services until September over a "resurgence in migrant intrusions in past weeks," port authorities said in a statement.

The rail motorway -- which only went into operation in March -- allows road hauliers to cross France in 22 hours, avoiding 1,200 kilometres (745 miles) of roads.

However migrants living in the infamous camp known as the "Jungle" near the port of Calais try and break into the trailers as part of their desperate efforts to reach Britain.

Port workers and business owners launched the go-slow operation on a highway around Calais after the rail motorway stopped running.

"The situation keeps getting worse. We don't know what to do anymore to be heard," said Antoine Ravisse, president of a citizens' movement protesting the migrant crisis in the northern port.

"The migrants, some of whom are armed, climb into the trailers, they rip the tarpaulins. Our clients lose confidence in us, sometimes their merchandise is destroyed. The cost is enormous," he added.

Around 4,500 migrants, mainly from Afghanistan and Sudan, live in the Jungle camp, according to an official estimate.